An internal combustion engine is difficult to start, in particular, the problem of a starting system of a high-power diesel engine is more prominent, the failure rate is high, the reliability is poor, in order to solve this problem, people always increase the power of a starter and a storage battery, although the internal combustion engine can be started in this way, since the starting torque of the internal combustion engine still exists, a starting current larger than 1000 A still exists, such that the high failure rate of the starting system cannot be solved fundamentally.
In order to reduce the starting torque of the internal combustion engine, people design a manual decompression starting device on a low-power internal combustion engine, before the internal combustion engine is started, firstly a valve is manually opened to ensure no compression resistance of the internal combustion engine, and after a crankshaft reaches a starting speed, the valve is manually closed, the shortcoming of this method is that both-hand operation is needed, thus being inconvenient to use, and in addition, the valve of a high-power multi-cylinder internal combustion engine requires a very large acting force to be opened manually, therefore the high-power multi-cylinder internal combustion engine is provided with no manual decompression device.
In order to change the manual decompression starting of the internal combustion engine into automatic decompression starting, people propose methods of acting on the valve by air pressure, hydraulic pressure and an electromagnet, but these methods have the shortcomings that a decompression structure occupies a large space, the necessary mechanical force and external electric force are large, numerous components are needed and failure is prone to occur.